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i8

The percentage by volume is found by dividing this result by the average

density of acetone oil, namely, 0-840.

4. Absorption of Bromine.—This is carried out as with crude methyl

alcohol (q.v.).

*
#  *

Acetone oils vary in composition with the quality of the, calcium pyrolignite
from which they are obtained, and with the conditions of the distillation, etc.

Light acetone oils are yellowish liquids of repulsive odour and burning, acrid

taste. They boil in general between 70° and too0 (mostly at; 70......80°), are soluble

to the extent of 40-50% in an equal volume of water and to the extent of <jo -0.5%
in four volumes of water, and contain 1)0-95% by volume of ketones calculated
as methyl ethyl ketone. Light acetone oils are used especially for the denatnra-
tion of alcohol and in different countries have, to satisfy definite conditions as
regards colour, density, boiling point, solubility in water, content, of ketones, etc,

Heavy acetone oils have a more pronounced yellow colour than the light
oils, are less soluble in water, and boil at 1.30--50°.

ACETIC   ACID
C2H(10 2 = 60-03 (60)

Various qualities are found on the market: Crude- pyroli'gneous acid,
brown, turbid liquid with a strong empyrenmatic odour, 1) about i'or.3,
containing 5-10% of acetic acid. Cwime.rcUd ace-He add, colourless or
yellowish liquid with more or less marked empyrcumul ic odour ; it may
contain 90-95% of acetic acid or may be. more dilute (30-60%), ibe principal
impurity being hydrochloric, sulphuric or sulphurous acid. The pure or
puriss. glacial acid is colourless, has a pure acetic odour and contains 96-

100% of the acid (D 1-0644......I>0553). the usual content being 96.......0,8% (D

1-0644-1-0604) ;  it boils at about iiB" and at about -|~ *<>" solidifies to
colourless, transparent, lamellar crystals.

Analysis of acetic acids, which may be contaminated with salts of copper,
lead, iron and calcium and with arsenic, hydrochloric, sulphuric, and sul-
phurous acids, and organic and pyrogenie substances, comprises mainly
the following determinations and tests :

1.  Specific Gravity.—-This is measured in the ordinary manner (hydro-
meter, Mohr's balance).    In the case of a pure acid, the content of acid
may be determined from the specific gravity by means of Oudemans' table,
which is given in the various books of chemical tables.

2.  Residue on Evaporation.-......-10 c.c. are evaporated by gentle heating

in a dish to ascertain if any carbonaceous residue (organic, matters) remains ;
this is then calcined, a solid residue, showing the presence of mineral sub-
stances.

3.  Metals.—1™2 c.c., diluted with 20 c.c. of water, should not be ren-
dered turbid by hydrogen sulphide (copper, lead), or by excess of amnunia
and ammonium sulphide (iron) or by ammonium oxalate (calcium).

4.  Arsenic.—i~2 c.c., treated with 5 c.c. of Hcttcndor/'s reagent,1 should
give no coloration within an hour.

1 Bettendorf's reagent is prepared by dissolving 20 parts of pure tin in <>5 parts of
pure concentrated hydrochloric acid at a gcjiitle heat, replacing tin; water evaporated,
and saturating with dry, gaseous hydrogen chloride.and should be as free as possible from organic matter, nitrites, nitrates, ammonia